AGE AT MENARCHE AND RISK OF CORONARY HEART DISEASE IN THE UK MILLION WOMEN STUDY

INTRODUCTION: Early menarche has been reported to increase coronary heart disease (CHD) risk but findings from prospective studies have been limited and the risks associated with a wide range of menarcheal ages have not been assessed as findings have been based on relatively small number of events. We examined the prospective relation between age at menarche and CHD in the Million Women Study.

METHODS: 1.2 million UK women completed a health and lifestyle questionnaire between 1996 and 2001 (mean age at baseline=56 years) and reported their age when they had their first menstruation (mean age at menarche=13 years). We excluded women with prior vascular disease or cancer and calculated relative risks using Cox regression with attained age as the underlying time variable.

RESULTS: After a mean follow-up of over 11 years, over 70,000 women had a first coronary event (hospitalisation or death). Women with earlier and later menarche had increasing CHD risks. As compared to women with menarche at age 13 years, the relative risks were 1.27 (95% confidence interval [CI] 1.22 to 1.31) for menarche at ≤10 years and 1.23 (95% CI 1.16 to 1.30) for menarche at ≥17 years after adjusting for body mass index, smoking, alcohol intake, physical activity and socioeconomic status. Further adjustment for parity, oral contraceptive pill use and postmenopausal status did not alter the results. This U-shape relationship was observed in lean, overweight and obese women.

CONCLUSIONS: In this cohort, both early and late menarche were associated with increased risk of developing CHD.